1. Field of Invention
The present invention relates to an imaging apparatus, in particularly to a thermal-sublimation imaging apparatus and a thermal sublimation printer using the same.
2. Related Art
Thermal-sublimation imaging technique is widely used in photo printing, and works according to the following principle. Dry solid ink on a ribbon, i.e., a mixture of a toning agent and a polymer thinly coated on the ribbon may be divided into yellow, cyan, and magenta, and the size of the ribbon is slightly larger than that of the photo paper to be printed. When printing, the photo paper and ribbon pass through a platen simultaneously, and are heated together under a print head. The heat-generating dots array of monocrystalline silicon with a diameter less than 40 μm on the print head is supplied with power, so as to melt the dry solid ink coated on the ribbon. During heating, polymer molecules are separated at about 320 Fahrenheit degrees. When the print head has passed, the temperature drops, and the ink is changed from gas state into solid state, thus the ink is embedded in the polymer, and then the polymer molecules are polymerized together. After one color is printed, the printing is repeated automatically to print next color. Accordingly, the ribbon is sublimated to generate a mixture of millions of colors on a photo paper, thereby achieving an optimal photo effect.
The printing process has three steps including paper pickup, paper feeding/reversing with ribbon spooling, and printing. In printing, only one color is printed on the paper at a time, and after transferring three colors onto the paper, a protection layer must be added. Therefore, the paper feeding/reversing with ribbon spooling step and the printing step must be repeated four times. In the printing step, a pressure is required between the platen and the print head to uniformly transfer the dyes onto the paper.
In the conventional thermal sublimation printers, in order to realize the actions such as providing pressure for printing, paper pickup, and paper feeding/reversing, a cam or other mechanisms are generally required to switch among these actions, thus increasing the manufacturing cost and the time for printing.